Conventional various control modules (e.g., engine control module, motor control module, automatic transmission control module) mounted on automobiles, farming machines, industrial machines and ships have been disposed within a vehicle interior room or an engine room. These control modules are generally constructed such that electronic components are mounted on a printed circuit board and the printed circuit board is fixed on a metallic base and is covered with a case.
Recently, studies have been made about a control module of the type in which the control module is mounted directly onto an intake manifold, i.e., on-engine type. Control modules using a printed circuit board are not applicable to the on-engine type because their heat resistance is about 120° C. Control modules using a ceramic circuit board are applicable to the on-engine type because their heat resistance is high, but are somewhat expensive.
On-engine type control modules, in comparison with those installed within a vehicle interior room or an engine room, are required to have not only high heat resistance but also high vibration resistance and complete air- and water-tightness. Such requirements are made not only for on-engine type control modules but also for sensor modules (e.g., pressure sensor module, air flow meter module).
To meet such requirements, as to a configuration of a module using a printed circuit board and applicable to the on-engine type, there is known such a configuration as in Japanese Patent Laid Open No. 2001-288333 wherein external lead terminals and a circuit board are formed integrally by transfer molding. There also is known such a configuration as in Japanese Patent Laid Open No. H7 (1995)-22722 wherein a connector and a circuit board are formed integrally by a low pressure (reduced pressure) molding method involving heat-curing a pasty resin. Further proposed are a module and a method of manufacturing the same, involving encapsulating with a thermosetting resin for the purpose of improving productivity and reliability and reducing size.